Wood is a natural resource that is found on trees. Trees are cut down so they, most famously, can be used to make objects like furniture. It's funny how humans think furniture is better than oxygen, because trees provide it.
A close-up of Astronaut John Grunsfeld shows the reflection of Astronaut Andrew Feustel, perched on the robotic arm and taking the photo. The pair teamed together on three of the five spacewalks during Servicing Mission 4 in May Space by Nasa®